The Sinclair QL Forum

Dave wrote:I don't know. I can honestly say I have no fondness for microdrives. I was actually physically bullied over them as a teenager. The other kids were playing with their shiny new 3.5" drives in 1985 when I got my first QL from Dixon's. I think it's fair to say I equate microdrives with asbestos, thalidomide and trickle down economics.

Ditto. They pushed the data read/write frequency too far, and at the same time made them incompatible with ZX tapes. I would have traded the extra 25K for the reliability I experienced with ZX system.

The relentless sound of the tape splice crunching past the head every 7 seconds, knowing I've just lost several hours work, still haunts me 30 years on.

Dave wrote:What IC is on the multiIO card on that?

W83787IF
W83758P

Nasta wrote:...115200 would be about the maximum.

From what I've read recently not many people have had much success with baud rates >115200 anyway. Apparently, even 16MHz AVRs have only achieved reliable 115200 between similar boards (same latency etc).

Nasta wrote:...all interrupts on the QL are level 2, so level 5 is still available and this is where a fast poll interrupt can be mapped.

I only mentioned level 4 for FN CPU since it would only require one inverter and one 2-input NAND to prioritise level 4 against concurrent level 2.

Nasta wrote:A long time ago I had a nice talk with Tony Tebby about some real time OS matters, and he very convincingly made a case for using a polling chain rather than multiple level interrupts.

The direct interrupt would only really be needed during development/exploratory phase of ESP-32 using the in-built serial server. From what I've seen of ESP-32 it would be quite possible to eventually upload a user program to act as server to QL polled interrupt (EXTINT). This could deal with any response delay and buffer data. Given the dual cores and available memory it could also do some useful pre-processing of data. Just provide a link on PCB to select UART IRQ (or GPIO as IRQ) : interrupt level/EXTINT.

BTW The ESP-32 firmware even includes an on-board BASIC! http://hackaday.com/2016/10/27/basic-in ... 2-silicon/

Silvester wrote:

Dave wrote:What IC is on the multiIO card on that?

W83787IF
W83758P

Excellent

It meets the PC97/98 standard, which means the code in SMSQ will run with very very little rework the 87307 which also meets the PC97/98 standard.

Hi,

Will Sernet be supported, as you know, Sernet needs STX / SRX split speeds to the operate.

The machine that has the SuperIO would have wifi and 10/100 ethernet and would not have the 8302/8049. I don't know if sernet would be supported by the hardware or not, but I don't think it would be as useful.

I never had problems with my microdrives, not on the Spectrum with Interface 1, nor on the QL. Well, I did have one problem when I bought a new JM QL, one drive didn't work. I took it back and they changed it for a JS QL instead. Nice one!

Since then, no problems. Maybe I'm just lucky?

I also don;t understand most of what Nasta says (types) but I do love reading it!


Cheers,
Norm.

I'll explain why I decided to not include microdrives on the Issue 8:

1. If Sinclair redesigned the QL for a version 2 any time from late 1984 onwards it would have had a 3.5" floppy instead of microdrives.
2. Anyone who has microdrives and floppies or HDs uses microdrives barely at all.
3. 33 years later, microdrives are the least reliable or secure storage medium.
4. Microdrives are huge and take up a lot of valuable real estate inside the QL's case.
5. I did a redesign of the microdrive PCB and came to realize it works by magic.
6. I changed the shape of the Issue 8 PCB, and there is no PCB where the microdrive cable lands.

And what reason could be for a storage device that you have not been able to buy any media for since 30 years?

Tobias

tofro wrote:And what reason could be for a storage device that you have not been able to buy any media for since 30 years?

Tobias

Nostalgia.
Software preservation.
Key cartridges.

But for any of those get and use an original QL I guess.